The invention relates generally to containment cases and, more particularly, to containment cases with enhanced impact resistance.
Gas turbine engines are extensively used to propel an aircraft. A typical turbofan engine includes large, ducted fans placed at the front of the engine. The fans serve to produce greater thrust and reduce specific fuel consumption. During the operation of such engines, there is a remote possibility that a foreign body, such as a bird, could impact the fan(s) and cause severe fan damage. That damage could result in part or all of a fan blade becoming detached from the hub and impacting the fan case, or casing. Such a detached fan blade could cause considerable damage to the aircraft powered by the engine if it were not contained by the fan case. Similar damage could also result if the fan blade suffered failure through fatigue. In order to prevent such damage, various containment systems have been employed. Conventional containment cases, or casings, are typically formed of a solid metal having a thickness sufficient to withstand the impact of a fan blade within the plane of the fan. However, blade containment achieved by these methods generally incurs significant additional weight.
Composite materials are being evaluated for use in containment cases and would provide considerable weight benefits. However, composites can be subject to puncture at the interior surface of the containment case. In particular, composite blade containment cases are susceptible to damage due to sharp object impact. Accordingly, it would be advantageous to provide a blade containment case with improved impact resistance.